1. Field of the Invention
The invention relates to facilitating physiological coherence (also referred to as entrainment or resonance) and more particularly, to systems and methods for using respiration-training or mental/emotional self-management techniques to achieve physiological coherence and/or entrainment. Systems and methods for monitoring respiration patterns to detect emotional/stress state are also disclosed.
2. Background of the invention
With the growing complexity of life, the relation between physiological conditions and emotional health becomes of increasing interest and importance. Many studies have shown that stress and other emotional factors increase the risk of disease, reduce performance and productivity and severely restrict the quality of life. To this end, the medical communities around the world continually seek remedies and preventive plans. Recently, a focus on the self-regulation of systems within the body has led to research in the areas of increasing performance and facilitating recovery from numerous health challenges. Such research has suggested a causal link to, for example, enhanced academic performance, communication and listening skills, faster reaction times and better coordination.
In the last 25 years, a variety of new techniques have been introduced as alternatives to more traditional psychotherapies or pharmaceutical interventions for improving mental and/or emotional imbalances, reducing stress and improving performance. In addition to the more psychological approaches like cognitive re-structuring and neurolinguistic programming, psychologists have employed several techniques from Eastern cultures to “still the mind” during focused meditation. In yoga, for example, one generally focuses on the breath or parts of the brain, whereas in qigong one focuses on the “dan tien” point (below the navel). In the Freeze Frame® (FF) and other related techniques, developed by the Institute of Heart Math in Boulder Creek, Calif., one focuses attention on the area around the heart. All these techniques focus attention upon areas of the body which are known to contain separate but interacting groups of neuronal processing centers, and biological oscillators with which they interact. The heart, brain, and the intestines contain biological oscillators known as pacemaker cells. By intentionally focusing attention on any one of these oscillator systems, one can alter its rhythms. This is at least true for the brain (meditation), yogic breathing (respiration) and other cognitively-directed paced-breathing techniques, the heart (Freeze-Framer (FF) and other HeartMath techniques), and most likely the gut (qigong). The body also contains other oscillating systems such as the smooth muscles of the vascular system. In U.S. Pat. No. 6,358,201, entitled “Method and Apparatus for Facilitating Physiological Coherence and Autonomic Balance,” which is assigned to the assignee hereof and hereby incorporated fully by reference, it was shown that the body's systems such as blood pressure rhythms (measured by recording pulse transit time (PTT), the heart (measured by a heart rate variability (HRV)), and the respiration system (measured by the respiration rate) can all entrain. Furthermore, they all synchronize to a frequency varying around 0.1 Hertz (Hz). Thus, one can intentionally bring these systems, acting as coupled biological oscillators, into synchronization with each other. In addition, in this coherent or resonant mode, several brain rhythms (measured by an electroencephalograph (EEG)) become more synchronized to the heart.
By applying spectral analysis techniques to the HRV waveform, its different frequency components, which represent the activity of the sympathetic or parasympathetic branches of the autonomic nervous system, can be discerned. The HRV power spectrum is divided into three frequency ranges or bands: very low frequency (VLF), 0.033 to 0.04 Hz; low frequency (LF), 0.04 to 0.15 Hz; and high frequency (HF), 0.15 to 0.4 Hz.
The high frequency (HF) band is widely accepted as a measure of parasympathetic or vagal activity. The peak in this band corresponds to the heart rate variations related to the respiratory cycle, commonly referred to as respiratory sinus arrhythmia (RSA). Reduced parasympathetic activity has been found in individuals under mental or emotional stress, suffering from panic, anxiety or worry, depression, high blood pressure, heart disease and many other disorders. As such, previous RSA training approaches have focused on increasing the HF peak in the HRV power spectrum. The low frequency (LF) region can reflect both sympathetic and parasympathetic activity, especially in short-term recordings.
While the FF technique described in previously incorporated U.S. Pat. No. 6,358,291 is a self-management technique which focuses on the heart, the respiratory cycle may also be linked to mental/emotional state and can be used to achieve physiological coherence and/or entrainment. Thus, there is a need to provide a method and apparatus for optimizing the respiratory cycle and RSA pattern in a manner that facilitates physiological coherence.